An exclusive investigative report by Reuters appears to confirm fears held by critics that the vast network of surveillance programs maintained by the National Security Agency is being used not only for countering international terrorism, but also for targeting common criminals within the U.S.

Though NSA officials and their backers have repeatedly said that the spy programs are designed to "keep America safe" from international terrorism, the new revelations show that domestic law enforcement is likely being supplied with data from these same operations.

According to the report, a secretive U.S. Drug Enforcement Administration unit—called Special Operations Division, or SOD—"is funneling information from intelligence intercepts, wiretaps, informants and a massive database of telephone records to authorities across the nation to help them launch criminal investigations of Americans."

Documents obtained by Reuters reveal that DEA agents or other law enforcement agencies are supplied with information used from "classified" sources to initiate investigations but that internal protocols demand that investigators then "recreate" the source of where the information came from so to keep SOD's involvement off the books.

Nancy Gertner, a Harvard Law School professor who served as a federal judge from 1994 to 2011, told Reuters she'd "never heard of anything like this."

From Reuters:

Gertner and other legal experts said the program sounds more troubling than recent disclosures that the National Security Agency has been collecting domestic phone records. The NSA effort is geared toward stopping terrorists; the DEA program targets common criminals, primarily drug dealers.

"It is one thing to create special rules for national security," Gertner said. "Ordinary crime is entirely different. It sounds like they are phonying up investigations."

Though the secretive and classified nature of these programs makes it impossible to know the degree to which they betray constitutional and legal norms, the revelations only deepen the suspicions about how the spying capabilities are being used by government agencies.

Glenn Greenwald, the Guardian journalist behind much of the recent reporting on the NSA spying programs, read the Reuter's article and tweeted in response:

This is big (though unsurprising) - from Reuters: US directs agents to cover up program used to investigate Americans http://t.co/4LTzQuO1sP

Defense attorneys who spoke to Reuters called the program "outrageous," "indefensible," and "blatantly unconstitutional."

"You can't game the system," said one former federal prosecutor. "You can't create this subterfuge. These are drug crimes, not national security cases. If you don't draw the line here, where do you draw it?"